why data class is hidden?

[HiroyukiTamura]

for example, class Indexed in package:more/src/iterable/indexed.dart can't be accessed from other package.
but I want to use class for generics just like indexed<E>(list).map((Indexed<E> item) {}
any solution?
thanks in advance.

[renggli]

This is an oversight, fixed in cec2e6a and 1.18.1.